Research efforts are currently devoted to synthesizing analogs of Coenzyme A which potentially can be used as active-site-directed irreversible enzyme inhibitors. Photoaffinity labels of the nitrene type and thiolesters of arsinous acids, e.g., S-cacodyl-CoA, are under investigation. These agents are to be tested as inhibitors on enzymes of the following classes: Hydrolase (e.g., acyl-CoA hydrolase), Transferase (e.g., 1-acylglycerol 3-P acyltransferase), and Lyase (e.g., citrate synthetase).